Siemens Aktiengesellschaft

Gerhard Schaich

Lothar Schmidt

Wolfram Ernst

Fritz Hlawa

Ludwig Schoenauer

Klaus Eberlein

A circuit arrangement for telecommunication switching systems, including PCM time division multiplex telephone switching systems, with double central switching matrix by which two corresponding line trunk groups comprising a sub-switching matrix each and a group control unit each, are allocated to each other in pairs via two time-division-multiplex lines. The line units and the PCM-lines leading to the central switching matrix, which are individually respectively allocated to the two line trunk groups, and which are connected with the respective sub-switching matrix of their own line trunk group during normal service, are switchable, during emergency service of one of the two line trunk groups, to the sub-switching matrix of the respective other line trunk group. In order that no calls already interconnected via the line units of the affected line trunk group up to the time of the switch-over are interrupted, each local control unit transmits all call data of interconnected calls to its associated control unit while still in normal service, on which basis the appertaining calls are securely interconnected within the sub-switching matrix of the associated line trunk group.

Circuit arrangement for telecommunication switching systems,

The switching network is tested by comparison of bit streams coming from the double part switching network parts; other parts of the exchange are tested by parity checking. Evaluation takes place at a central location; when a parity error is found in the transmission in a direction of transmission, the parity bit generated for transmission in the other direction of transmission is falsified.

Method for monitoring information transmission in connected through

A circuit for a centrally controlled time division multiplex telecommunication exchange having PCM line/trunk groups connected to a switching network wherein each line/trunk group comprises a plurality of line units to connect one time division multiplex interexchange trunk each and is connected to a switching network over a time division multiplex line. Two line/trunk groups are assigned to each other in pairs. The connection devices which are assigned to one and to the other of two line/trunk groups and which in normal operation are connected with the time division multiplex switching device of each of their own line/trunk group can be changed over during emergency operation of one of the two line/trunk groups to the time division multiplex switching device of the other line/trunk group.

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Munich, Germany

Gerhard Schaich